“I forgot,” explained the humbled Tom.  “But that’s a funny way to dig.  Don’t you think so, Mr. Harrison?”

“That’s the way they dig down in this country of pure sand.”

“Well, all I’ve got to say is that when I dig—­”

What Tom said might have been interesting if it had been heard.  But just at that instant a shot rang out from the group of workers.  The boys stared in amazement horrified at the thought of what might have happened.  In an instant their worst fears were confirmed.

Their startled eyes beheld the negroes dragging one of their number from the excavation under the watchful eye and threatening muzzle of Lopez’s deadly rifle.  One of the unfortunate negroes had thoughtlessly broken his resolve and had spoken.  He had paid dearly for his mistake.  Under the stern command of the rifle muzzle the others renewed their task, glancing apprehensively at the man behind the grim weapon whose messengers were all messengers of swift and certain death.  They were visibly affected.

Instinctively the boys drew their automatics while Harrison possessed himself of his revolver and made ready to use it if necessary in self defense.  No one could guess the result should Lopez discover their whereabouts.  Their position was now seen to be a most dangerous one, for they lay but a few yards beyond the rim of the excavation in which the men were working.  Lopez was opposite.

“If that man ever sees us here,” whispered Harry, “we’re gone.”

“You’re right, we’re gone,” declared Arnold.  “That man don’t think any more of shooting a man than he did of shooting that big snake.  He’s absolutely bloodless, I believe.”

“Look at Wyckoff down in the excavation walking back and forth and around,” Tom said pointing to the figure mentioned.

“He surely isn’t going to let anything get past him,” agreed Jack.  “He walks round and round and round as the men dig.”

“And they are digging at a rapid pace, too,” Frank put in.  “At that rate they ought to get the treasure before long.”

“I’m a little afraid,” Harrison dissented.  “It looks bad.”

“What looks bad?  The two men may quarrel.”

“There’s always a possibility of that,” agreed Harrison, “but I wasn’t thinking of that.  It looks to me that the sand will probably be softened by the rising tide.  If so, they can’t remain in the excavation to dig for the treasure at all.  They must quit.”

“If that happens, I can see some more dead niggers,” Tom asserted.  “That man Lopez seems to be itching to shoot someone.  If he is foiled in his last desperate attempt to get that treasure, I can see trouble ahead for someone who is near him when it happens.”

Wyckoff now came out of the hole to join Lopez on the rim of the crater made by the toiling negroes.  Without saying a word he evidently asked Lopez for something to drink, for he made a motion as if drinking from a cup, Lopez without taking his eyes off the workers jerked his head in the direction of the boat.